Note: Descriptions are shown in the official language in which they were submitted.
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AN ASSEMBLY OF AN OVERMOLDED ELEMENT HAVING HOOKS AND OF
A MOLD INCLUDING A PEDESTAL
The present invention relates to an overmolded
element having hooks that is designed to be overmolded in
an overmolded article while said article is being molded,
the article being, in particular, a foam article, and in
particular a cushion for a motor vehicle. The present
invention also relates to an assembly made up of an
overmolded element of this type and of a mold including a
pedestal that co-operates with the overmolded element
during the molding. The present invention also relates
to a molded article having a main body made of a molding
material, in particular of a foam, and an overmolded
element of the above-mentioned type overmolded in the
main body. The present invention also relates to a unit
made up of a molded article of this type, in particular a
motor vehicle cushion, and of a cover that covers the
outside surface of the molded article, the mutual
fastening between the molded article, in particular the
molded cushion, and its cover, taking place by means of a
hook-and-loop device, the hooks stemming from the element
having hooks overmolded in the molded article, while the
loops stem from the cover. The present invention also
relates to a method of manufacturing a molded article of
the above-mentioned type.
Nowadays, in order to fasten a fabric cover to the
outside surface of a molded thermoplastic foam cushion
for a motor vehicle, it is common practice to use a hook-
and-loop self-fastener or "touch fastener".
Conventionally, an overmolded element constituted by a
strip of thermoplastic material has a face from which
hooks project while a metallic resin is fastened to the
other face. Then, the overmolded element having hooks is
placed over a pedestal, in particular formed at the
bottom of the mold, a cavity, in particular, being formed
in the top surface of the pedestal. That cavity formed
at the bottom of the mold in the top surface of the
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f
pedestal has vertical walls over which the overmolded
element having hooks is placed with the hooks disposed on
the inside of the cavity while the foam is being poured
in for obtaining the molded article by molding. At the
bottom of the cavity, a magnet is disposed so as to
attract the overmolded element via the metallic resin and
so as to hold it stationary in contact with the top edges
of the vertical walls, with good sealing-off relative to
the foam. After the foam has been cast and left to cool
and therefore to set, the molded article is obtained in
which the overmolded element having hooks is overmolded,
the hooks then appearing on the outside surface of the
molded article and being able to co-operate with loops
(or indeed with hooks when the self-fastener device is a
hook-in-hook device) associated with a cover, e.g. in the
form of a fabric, so as to fasten said cover around the
molded article by the hooks and the loops co-operating
with one another.
That conventional technique suffers from various
drawbacks. Firstly, it requires the cavity for
protecting the hooks to be formed in the top of the
pedestal, e.g. by machining it. In addition, during the
molding process, that technique requires a considerable
amount of labor for positioning the overmolded element
over the pedestal, which is detrimental to large-scale
fabrication. In addition, the magnets placed in the
protective cavity formed in the pedestal deteriorate over
time due to the molds being heated and cooled in
alternation. There comes a time during the production
process when those magnets need to be replaced and that
operation is costly and takes a considerable amount of
time.
In a first aspect, an object of the present
invention is to overcome the drawbacks of the prior art
by proposing a system for overmolding the overmolded
element having hooks in the molded article that does need
either a protective cavity to be provided, or a magnet to
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be used, without the protection of the hooks from the
cast foam during the molding being less good.
In a first aspect, the invention provides an
assembly comprising firstly an overmolded element having
hooks, designed to be overmolded in a molded article, the
overmolded element forming an open internal space defined
by two end side walls and a bottom, from which at least
one hook stemming from the element projects or from which
some hooks stemming from the element project; and
secondly a mold having its internal wall(s) defining an
internal volume that is the same shape as the article to
be formed by molding in the mold, at least one pedestal
projecting into the internal volume from said inside
wall(s), the overmolded element having hooks being in
contact with the pedestal while the molding foam is being
cast, the pedestal including a rail-shaped portion having
two opposite outer side faces, which are, in particular,
parallel faces, said assembly being characterized in
that, while the foam is being cast, the respective end
side walls of the overmolded element are in contact with
the respective opposite outer side faces, without hooks
being interposed between them.
In accordance with the invention, the pedestal is
clamped between the two side walls, so that said side
walls bear against the two side faces, in particular in
resilient manner, so as to provide sealing from the
liquid foam being poured into the internal space at the
hooks, without said hooks being damaged. In particular,
said hooks are not gripped vice-like between the walls of
the pedestal and of the overmolded element, which two
walls bear against each other and are therefore not
compressed as in the prior art.
Thus, good sealing from the foam is provided at the
contacts between the side faces of the pedestal and the
walls of the overmolded element so that the hooks are
well protected. It is no longer necessary firstly to
make provision to form a cavity in the top of the
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pedestal, or secondly to provide a system having magnets
and metal materials, or indeed to provide other complex
devices for protecting the hooks from the liquid foam
poured in during the molding, in order to guarantee good
positioning of the overmolded element and good protection
of the hooks. It is thus possible to simplify the method
of placing the overmolded element having hooks in the
mold prior to molding, and in particular of positioning
it, and, in addition, the mold itself is of simpler
structure. At the end of the molding, hooks are obtained
that appear outside the molded article, at the bottom of
a groove or trench that is narrow (in particular as
narrow as the pedestal), and in particular that can be
narrower than in the prior art.
In a preferred embodiment, the element having hooks
clamps the pedestal between its two side walls, in
particular with force.
In particular, the contact between the respective
walls of the overmolded element and of the pedestal takes
place along respective lines, in particular straight
lines. Preferably, the innermost end edges of the two
side walls are straight in shape, preferably being
mutually parallel, and, as seen in plan from above, the
two outer side faces of the rail have the same straight
shape, so that said respective contact lines are
straight.
In an improvement, the contact between the element
having hooks and the pedestal takes place by clipping.
Preferably, while the foam is being cast, some of
the hooks, and in particular all of the hooks of the
overmolded element having hooks, are some distance from
the rail, and in particular from its top. Optionally,
they may be flush therewith, i.e. the tops of the hooks
may touch the top of the rail, but without the rail
applying any pressure on them, and in particular without
said rail deforming them.
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Preferably, no hook projects from the inside
surfaces of the end side walls, all of the hooks
projecting from the bottom only of the element having
hooks.
5 In a preferred embodiment, each side wall of the
element having hooks has an innermost end edge, the
height of the highest point of the hooks being less than
the height of the innermost end edges; and the pedestal
includes a rail-shaped portion having two opposite outer
side faces that are spaced apart and that have shapes
that are substantially identical to the shapes of the end
edges of the side walls of the overmolded element, and a
thickness of the rail, i.e. a distance between the two
side faces measured in a given direction, being just
greater than a distance between the two end edges of the
two side walls in said given direction.
Preferably, the two side walls are inclined slightly
towards one another, in particular by having, as seen in
cross-section, a hook shape, a C-shape, a circularly
arcuate shape, or an analogous shape.
Preferably, the overmolded element also has front
and back walls, which extend transversely relative to the
side walls, and the pedestal has a top having a shape
that is substantially complementary to the shape of the
top edges of the front and back walls, so that it can
come to rest against the top edges of the walls,
optionally with sealing ribs being interposed that extend
along the two top edges of the front and back walls.
The open internal space within which the hooks lie
is thus closed completely, and the hooks are then
particularly well protected from the foam firstly at the
contacts between the two side faces of the rail and the
two side walls of the overmolded element, and secondly at
the front and back walls and at the top of the rail.
Preferably, the respective top edges of the front
and back walls are at respective heights greater than the
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highest point of the hooks, but less than the heights of
the top edges of the two side walls.
In a preferred embodiment, one or more sealing ribs
are provided that extend(s) along a respective one or
both of the top edges of the front and back walls.
Preferably, in cross-section, at least part of the
top face of the overmolded element having hooks, between
the two side walls, is substantially circularly arcuate
in shape, in particular in the zone from which the hooks
stem.
In another embodiment, each innermost top edge forms
a curved line, in particular a circularly arcuate line,
and, as seen in plan from above, the two side faces have
shapes identical to said curved lines, said respective
lines of contact being constituted by said curved lines.
Preferably, the base plate of the overmolded element
extends outwards beyond the two side walls, thereby
forming one or more outside brims.
In the finished molded article, these two brims are
totally surrounded by foam, and this anchoring in the
foam procures excellent strength for the fastening of the
overmolded element to the molded article. The good
anchoring of the molded article in the foam at the end of
molding guarantees that the overmolded element remains
properly bonded to the molded article while the
overmolded element (which is then anchored and overmolded
in the molded article) is being unclipped from the
pedestal.
Good anchoring of the overmolded element in the foam
of the molded article is facilitated even further by the
fact that the foam is in contact with the top surfaces of
the side walls.
Preferably, one or each side wall has an outside
rib, the rail having its greatest thickness at each rib
or at said ribs, the two ribs being in particular at the
same level, and said thickness of the rail being the
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distance between the two outermost points of said two
ribs.
The present invention also relates to a molded
article having a main body made of molding material, in
particular of a thermoplastic foam, and at least one
overmolded element having hooks of an assembly of the
invention, which element is overmolded in the molded main
body, the foam being in contact with the overmolded
element, in cross-section over the entire periphery of
the overmolded element, with the exception of the open
internal space that extends from one inside top edge to
the other inside top edge of the two side walls, so that,
above the overmolded element, a groove is formed that
opens out to the outside of the molded body, the groove
in particular having a shape complementary to the shape
of a rail having one or more thicknesses corresponding to
the distance(s) between the two inside top edges of the
two side walls of the pedestal of an assembly of the
invention.
The present invention also provides a unit made up
of a molded object of the invention and of a cover or a
covering, in particular made of fabric, covering the
outside surface of the molded article while snugly
fitting the shape of said outside surface.
The present invention also provides a unit
comprising a molded article and a cover that covers the
outside surface of the molded article at least in part,
at least one longitudinal groove or trench being formed
in the molded article while being open to the outside, at
least one element having hooks being overmolded in the
molded article so as to form the bottom of the groove at
least in part, some hooks and preferably the hooks
penetrating into openings in loops stemming from the
cover so as to hook therein and thereby fasten the cover
to the molded article.
In a second aspect of the invention, independent
from the first aspect and forming an invention in itself,
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at least two overmolded elements having hooks are
provided that form the bottom of the trench at least in
part by being placed one behind the other in the
longitudinal direction, the two elements having hooks
being separated from each other by an intermediate zone
in which there is no element having hooks; and means are
provided for preventing the cover from riding up towards
the top of the trench, in particular at the or at each
intermediate zone.
Thus, hook-and-loop self-fasteners are used for
fastening the cover around the article but in a smaller
quantity, thereby having a very favorable effect on the
cost, without, however, adversely affecting the great
simplicity with which the assembly can be manufactured
and fitted, or the reliability of the fastening, in
particular without adversely affecting its pull-out
strength, which is preserved or indeed improved by the
anti-ride-up means.
Preferably, the loops stem from the outside surface
of a pocket fastened to the cover, and the means for
preventing the riding-up effect are constituted by a wire
that extends inside the pocket.
Thus, compared to the prior art in which hook-and-
loop systems are also provided for fastening the cover to
the molded article, fewer hooks are provided, thereby
considerably reducing the costs, and, instead, the rigid
wire is provided, which wire is made in particular of a
thermoplastic material, which is must less costly but
that nevertheless makes it possible to obtain upward
pull-out strength that is as good or even better. In
addition, with a trench that does not extend straightly,
but rather that includes curved portions, it is possible,
nonetheless, to use straight overmolded elements,
adapting them to match the curved portions being
facilitated by the fact that they can be spaced apart
from one another and do not need to be placed
continuously over the entire length over which the trench
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extends, which elements would otherwise need to have
corresponding curved shapes.
Preferably, the loops stem from the outside surface
of a pocket fastened to the cover, and the means for
preventing the riding-up effect are constituted by a wire
that extends inside the pocket.
Preferably, the loops stem from the bottom portion
of the periphery of the pocket, in particular from this
portion only.
In an improvement, the length of the intermediate
zone, i.e. the distance between the two successive
adjacent overmolded elements in the longitudinal
direction is such that, without the wire, a riding-up
effect appears; and the material and the dimensions of
the wire are such that it is sufficiently rigid for the
riding-up effect to be smaller when it is received in the
pocket, and, in particular, for there no longer to be any
riding-up effect.
Thus, by providing a rigid wire, in particular a
wire that is rigid in the vertical plane, there is no
longer any riding-up effect, and the cost of material for
forming the overmolded elements is lower, since said
overmolded elements extend over a smaller proportion of
the length over which the trench extends. In addition,
inserting the element having loops into the trench is
facilitated, since the wire has a support and guidance
function for such insertion. In addition, with a trench
that does not extend straightly, but rather that includes
curved portions, it is possible, nonetheless, to use
straight overmolded elements, adapting them to match the
curved portions being facilitated by the fact that they
can be spaced apart from one another and do not need to
be placed continuously over the entire length over which
the trench extends, which elements would otherwise need
to have corresponding curved shapes.
In a preferred embodiment, in cross-section, each
overmolded element having hooks has a U-shape or a C-
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shape, the two branches of which shape extend towards the
outside of the groove, the inside surface of the U-shape
or of the C-shape having two distal end segments from
which no hook projects, and an intermediate bottom
5 segment from which the hooks of the overmolded element
having hooks project.
In an advantageous embodiment, the groove has two
side faces formed by the material of which the molded
article is molded, which faces extend from the outside to
10 the respective top or distal edges of the branches of the
U-shape of each element having hooks and the respective
inside surfaces of the two branches of the U-shape or of
the C-shape are flush with the respective side faces.
In particular, the side faces of the groove are
vertical and come into register with the inside top edges
of the respective branches of the U-shape or of the C-
shape.
In a preferred embodiment, the groove includes at
least one segment of curved shape in which at least one
overmolded element extends that is of straight or curved
shape, the length of the overmolded element being less
than the length of the curved segment.
Preferably, the width of the groove is defined as
being the shortest distance between two of its facing
walls, and in particular when the elements having hooks
are aligned in a given direction, the width of the trench
is measured perpendicularly to said given direction, and
the width dimension of the element having loops excluding
the loops, i.e. the sum of the width dimension of the
wire and of twice the thickness of the pocket (excluding
the loops), is substantially equal to the width of the
trench, while nevertheless being just less than said
width of the trench.
Preferably, the distance between the respective
innermost points of the top edges of the two branches of
the U-shape or of the C-shape of each overmolded element
is substantially equal to the width dimension of the
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element having loops excluding the loops, i.e. the sum of
the width dimension of the wire and of twice the
thickness of the pocket (excluding the loops), while
nevertheless being just greater than this width
dimension.
Preferably, the pocket is fastened to the cover, in
particular by being sewn thereto, at the superposition of
two edges of two pieces or sheets of the cover.
Preferably, the distance over which the intermediate
zone extends between the at least two overmolded elements
having hooks is greater than 50% of the largest
dimension, in particular the length dimension, of each
overmolded element, and is preferably greater than the
largest length dimension of each overmolded element.
Preferably, the distance between the at least two
overmolded elements is greater than 20 millimeters (mm),
in particular greater than 100 mm, and in particular lies
in the range 100 mm to 500 mm.
Preferably, the wire has a cross-section that is of
oval shape, and in particular the major axis of the oval
shape extends in the direction going from the bottom of
the trench outwards, i.e. substantially perpendicular to
the base of each overmolded element.
In a particularly preferred embodiment, the wire has
a square or a rectangular cross-section, the corners of
which are rounded, and in particular the length, when the
wire has a rectangular cross-section, extends in the
direction going from the bottom of the trench towards the
outside.
Thus, by providing a rigid wire, there is no longer
any riding-up effect and the cost of material for forming
the overmolded elements is lower, since said overmolded
elements extend over a smaller proportion of the length
over which the trench extends. In addition, inserting
the element having loops into the trench is facilitated,
since the wire has a support and guidance function for
such insertion. In addition, with a trench that does not
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extend straightly, but rather that includes curved
portions, it is possible, nonetheless, to use straight
overmolded elements, adapting them to match the curved
portions being facilitated by the fact that they can be
spaced apart from one another and do not need to be
placed continuously over the entire length over which the
trench extends, which elements would otherwise need to
have corresponding curved shapes.
In a preferred embodiment, the trench includes at
least one segment of curved shape in which at least one
overmolded element extends that is of straight shape, the
length of the overmolded element being less than the
length of the curved segment.
Preferably, the shape of the pocket when the wire is
inserted therein is at least in part complementary to the
shape of the cross-section of the zone of the top faces
of the elements having hooks from which the hooks stem,
and in particular the wire is of circular section while
said zone has a circularly arcuate section.
Preferably, the pocket is fastened to the cover, in
particular by being sewn thereto, at the superposition of
two edges of two pieces or sheets of the cover.
Preferably, the width of the trench or groove is
defined as being the shortest distance between two of its
facing walls, and in particular when the elements having
hooks are aligned in a given direction, the width of the
trench is measured perpendicularly to said given
direction, and the width dimension of the element having
loops, i.e. the sum of the width dimension of the wire
and of twice the thickness of the pocket, is
substantially equal to the width of the trench, and in
particular just less than said width of the trench.
The present invention also provides a method of
manufacturing a molded article, in particular a unit in
the second aspect of the invention.
The method of the invention for manufacturing a
molded article by molding, in particular a molded article
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in the second aspect of the invention, includes the steps
that consist in taking a mold having the same shape as
the article that is to be molded, a rail-shaped pedestal
projecting from a wall of the mold defining the volume of
the mold, is characterized by the step that consists in
clamping the pedestal by an overmolded element having two
side walls that are spaced apart so that the two side
walls of the element having hooks come to bear against
two faces of the pedestal along at least two respective
lines of contact, in such a manner as to seal off the
internal space between the two walls of the overmolded
element, and in pouring in the foam for molding the
article.
In a third aspect, independent from the first and
second aspects and forming an invention in itself, the
present invention also provides an overmolded element
having hooks. However, it may be designed to be part of
an assembly of the first aspect of the invention and/or
to be part of a unit of the second aspect of the
invention.
In the third aspect of the invention, the overmolded
element having hooks including two side walls that are
spaced apart from each other and a bottom in such a
manner as to form an open internal space having a largest
width measured in a direction extending from one wall to
the other, in particular perpendicularly to the two
walls, and at least one hook, and preferably a plurality
of hooks, stemming from the bottom, is characterized in
that the top or distal portions of the two side walls are
inclined relative to each other so that the distance
between the two innermost points of the top edges of the
two walls is less than said largest width.
Preferably, in cross-section through the walls, the
bottom is constituted by a central straight segment ended
on either side by a respective right or left segment that
is substantially circularly arcuate in shape, in
particular in the zone from which the hooks stem.
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Preferably, the hooks of the overmolded element
project from the bottom only of the internal space.
An embodiment of the invention is described below
with reference to the drawings, in which:
= Figure 1 is a perspective view from above of an
overmolded element having hooks of the invention;
= Figure 2 is a section view on line A-A of
Figure 1;
= Figures 3A, 3B, and 3C are section views of
portions of respective molded articles of the invention,
each of which includes the overmolded element of
Figures 1 and 2;
= Figures 4A and 4B are side views showing the
overmolded element having hooks of Figures 1 and 2, and
respective pedestals, each of which is in the shape of a
rail over which the overmolded element having hooks is
positioned;
= Figures 5A and 5B are views similar to the views
of Figures 4A and 4B, but showing the state in which the
respective rail-shaped pedestal is inserted with force
(in the manner of a clip) in such a manner as to protect,
in sealed manner, the internal space for receiving the
hooks inside the overmolded element having hooks, the
assembly of Figure 5A corresponding to the molded article
of Figure 3A, and the assembly of Figure 5B corresponding
to the molded article of Figure 3B;
= Figure 6 is a cross-section view of an element
having loops of the invention, stemming from a cover
designed to cover the molded article of Figure 3;
= Figures 7 and 8 diagrammatically show how the
element having loops and the element having hooks co-
operate at the bottom of the trench in the molded article
of Figure 3 when it is covered by a cover including the
element having loops of Figure 6, when (Figure 8) the
wire made of a rigid plastics material is inside the
pocket, and when (Figure 7) it is not thereinside;
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Figure 9 diagrammatically shows another embodiment
of an overmolded element having hooks in a cross-section
view identical to the Figure 2 view;
= Figure 10 is another possible embodiment of a
5 pedestal of an assembly of the invention in a view
identical to Figure 4 or Figure 5;
= Figure 11 is a section view through a trench of
the molded article of an assembly of the invention;
= Figure 12 is a view identical to Figure 11 of
10 another embodiment of an assembly of the invention;
= Figure 13 is a diagrammatic section view of an
embodiment of a cover for covering a molded article of
the invention;
= Figure 14 is a diagrammatic section view of
15 another embodiment of a cover for covering a molded
article of the invention;
= Figure 15 is a view of a molded article, above a
trench which, in this embodiment, is made up of curved
segments and of straight segments;
= Figure 16 is another possible embodiment of a
pedestal of an assembly of the invention in a view
identical to Figure 4 or Figure 5; and
= Figure 17 is a section view identical to the
Figure 2 view showing another embodiment of an overmolded
element having hooks that has a flat bottom from which
the hooks stem.
In the figures, and in particular in Figure 1, a
perspective view is shown of an overmolded element having
hooks in a third aspect of the present invention and that
can be implemented in the first and/or second aspects of
the present invention. The element 1 is designed to be
placed in a mold to form a molded article by molding, the
article to be molded being made of a molding material, in
particular of a foam, and more particularly of a
thermoplastic foam. When the foam is poured into the
mold, said foam comes in liquid manner into contact with
the overmolded element, and then, by setting, fastens to
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the overmolded element. When the foam is poured into the
mold, the aim is for the hooks to be protected so that
the foam does not come to pollute them by penetrating
under the hooks, because, once the foam is under the
hooks, they become unusable and can no longer co-operate
with the loops to perform their hooking and hook-in-loop
fastening function.
The overmolded element 1 includes a plate 2 having a
rectangular base of long length L and of width f. The
length L extends in the longitudinal direction of the
overmolded element while the width ? extends in the
transverse direction. Two side walls 3 and 4 extend from
the top side of the plate 2. Each of these side walls 3
and 4 has a top edge, which, in this example, is
constituted by a surface that is substantially horizontal
to the figure, and each top edge has a line 5 and 6 made
up of the points of the top edge that are innermost, i.e.
that are closest to the other wall. In cross-section, in
particular as in Figure 2, each of these lines 5 and 6
forms a respective innermost point. These two lines 5
and 6 are straight in this example. In another
embodiment, shown in Figure 9, these top edges are not
necessarily plane surfaces, and may be stepped. Thus, in
Figure 9, the top edge has a horizontal first face
(corresponding to the top surface of the wall 3 excluding
the rib) followed by a second horizontal face (the top
face of the rib), stepped relative to the first face and
ended by a curved portion extending from the innermost
point of the second horizontal face to the innermost
point of the curved portion that corresponds to the
innermost point of the top edges of the walls 3 and 4.
Thus, in cross-section, and in particular in section
on A-A of Figure 1, and as shown in Figure 2, the
overmolded element is substantially U-shaped or C-shaped,
the branches of the U-shape or of the C-shape being
constituted by the two walls 3 and 4.
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The inside surface of the U-shape is made up of
three segments, namely two end segments, each of which
extends from the innermost point 5, or from the innermost
point 6, to a bottom intermediate segment that is defined
by the outermost hooks 38 on either side. Thus, in the
two end segments, there are no projecting hooks, and all
of the hooks of the overmolded element project from the
bottom intermediate segment.
In order to define the bottom of an overmolded
element of the present invention with precision, a first
definition method consists in considering the hooks and
in defining the bottom as being the smallest surface
defining the internal space within which all of the hooks
lie.
A second method consists, in each cross-section, in
projecting the two innermost points (5 and 6) vertically
(i.e. perpendicularly to the plane of the base plate in
Figure 2, for example) onto the inside surface defining
the internal space so as to obtain the two projected
points 5' and 6' between which it is considered that the
bottom extends.
In order to define the bottom of an overmolded
element of the invention, it is possible to use either
one of the two methods.
In Figures 1 and 2, the distal end portions of the
side walls 3 and 4 are inclined slightly towards each
other. Thus, in cross-section, e.g. at the section A-A,
the overmolded element 1 defines an open internal space
defined by the two walls 5 and 6 and by the top face of
the plate 2. As shown, this internal space preferably
has a floor 7 forming the bottom of the open internal
space defined by the overmolded element, which space is
C-shaped in this example. All of the hooks 38 project
from this floor or bottom 7, while no hook projects from
the inside surfaces of the two end walls 3 and 4. Said
hooks 38 can be arranged in any manner that is desired,
and preferably, as shown, they are arranged in rows and
CA 02787355 2012-07-16
18
in columns, in particular as shown with, in any given
column, their heads pointing towards the left and towards
the right of the figure in alternation.
The longest distance Do, measured in the direction
perpendicular to the walls, i.e. in the direction
horizontal to Figure 2, is the distance between the two
walls at the height h. It is greater than the distance do
between the two end edges. The same relationship is
verified in the embodiment shown in Figure 9. In
Figure 2, the embodiment is such that the cross-section
is the same for all of the cross-sections along the
longitudinal direction between the front and back walls 8
and 9, because the walls and the edges are straight in
this example. However, it is possible to consider an
embodiment in which said cross-section varies, e.g. in
which the walls and the edges have a certain amount of
curvature seen in plan from above, e.g. circularly
arcuate or oval curvature, or curvature of any other
imaginable shape. The relationship that Do is greater
than do is then valid in each cross-section.
The overmolded element also has a front wall and a
back wall 8 and 9. The front and back walls 8 and 9 and
the side walls 3 and 4 and the bottom floor 7 define the
open internal space within which the hooks lie. Each
front and back wall 8 and 9 has a respective top edge 10
and 11 that extends from one side edge 5 to the opposite
other side edge 6. These edges 10 and 11 are C-shaped in
this example. Sealing gaskets 13 extend along the top
edges 10 and 11 of the front and back walls 8 and 9.
Seen from above, the inside top edges of the walls 8
and 9 are straight lines. These lines may be otherwise
than straight and have any shape whatsoever, in
particular by having one or more curved portions.
The above-described element 1 is designed to be
placed in a mold, into which liquid foam is poured,
which, by setting, is fastened to the side walls 5 and 6
and to the bottom surface of the plate 2 and to the
CA 02787355 2012-07-16
19
outside faces of the front and back walls 8 and 9, so as
thus to fasten the hooks to the molded foam article.
Inside the mold, at least one pedestal 12 in the
shape of a rail projects from the inside wall 16 of the
mold that defines the volume having the shape of the
article that is to be manufactured by molding. It is
possible to provide one or more pedestals as a function
of the number of trenches that are to be formed in the
finished molded article in order to place hooks therein.
In particular, it is possible to provide an array of
pedestals that form an array of trenches, and some of
them may be curved. In order to prevent the foam from
being poured over the hooks, or from coming into contact
therewith, the hooks should be protected from coming into
contact with the poured foam while said foam is being
poured in. To this end, the overmolded element(s) having
hooks is/are clipped or clamped with force over the
pedestal(s), with the hooks facing towards the pedestal.
Over any given pedestal, it is possible to place a single
overmolded element or to place a plurality of them, one
behind the other, in which case they can either be placed
some distance apart from one another, as in the second
aspect of the invention, or very close together, or else
indeed end-to-end if so desired.
The rail 12 has two opposite side faces 30 and 31.
Seen from above, i.e. seen looking along the arrow F of
Figures 4 and 5, these faces are in the shape of straight
lines. They can thus have the same shape as the inside
top edges 5 and 6 of the two side walls 3 and 4.
The distance D between the two faces 30 and 31, as
measured in the direction (horizontal to the figure)
perpendicular to the two faces 30 and 31, which direction
corresponds to the thickness of the rail, is
substantially equal to, while being slightly greater
than, the distance do, measured in the same direction
between the two top edges 5 and 6 of the side walls 3 and
4.
CA 02787355 2012-07-16
When the rail does not have a constant thickness
along the longitudinal direction (perpendicular to the
plane of Figures 4 or 5) along which it extends, the
thickness D measured in each cross-section is
5 substantially equal to, while nevertheless being slightly
greater than, the distance do between the two innermost
end edges 5 and 6 at the level (along the longitudinal
direction) where the measurement is taken, the shapes of
the faces of the rail being complementary to the shapes
10 of the end edges. Thus, for example, it is possible to
provide a circular arc shape rather than a straight shape
for the edges 5 and 6 and for the faces 30 and 31, the
important thing being that the faces and the edges have
substantially the same shape in order to provide sealing
15 from the foam when the rail is inserted between the side
walls.
As shown in Figures 5A and 5B, when the overmolded
element 1 is in contact with the faces 30 and 31 of the
pedestal 12 during the molding, this contact takes place
20 over at least the straight lines defined by the end edges
5 and 6. In the embodiment shown, this contact takes
place over planes containing these lines.
In addition, the rail 12 has a top portion of shape
complementary to the shape of the top edges 10 and 11 of
the front and back walls 8 and 9. Thus, in this example,
the top of the rail 12 is C-shaped or is circularly
arcuate in shape corresponding to the C-shape or to the
circularly arcuate shape of the top edges of the front
and back walls 8 and 9. By coming to press the element 1
so that its two side walls come to clamp the pedestal 12
between their two edges 5 and 6, these two edges are
moved slightly apart from each other so as to enable the
rail to pass into it until its top 15 comes into contact
with the two top edges 10 and 11 of the side walls 8 and
9. The resilience of the two top end edges means that
they provide sealing where they come into contact with
the corresponding faces of the rail, since the two walls
CA 02787355 2012-07-16
21
tend to return towards each other by resilience, while
the sealing ribs 13, which find themselves between the
top of the rail 12 and the top edges of the walls 8 and
9, provide excellent sealing for the hooks while the foam
is being poured in.
In an improvement shown in Figure 10, it is possible
to provide two ribs that project laterally from the two
side faces 30 and 31 of the rail. The largest width of
the rail in any given cross-section is the distance D
between the two outermost points of the two ribs, and
this distance D is greater than the distance do.
In another embodiment shown in Figure 16, it is
possible to provide two longitudinal channels in the two
opposite side faces 30 and 31, which channels are
designed to receive the end side edges by snap-fastening.
The above-described two embodiments are improvements
using clipping or snap-fastening. However, they are not
necessary per se to obtaining the effect of the
invention, which effect is obtained whenever a pedestal
is inserted between the two side walls with mutual
contact being maintained, e.g. by the fact that the two
walls that have been moved apart outwards tend to return
inwards while bearing against the rail.
Once the foam has been cast and said foam has set,
the molded article is removed from the mold. A
longitudinal trench 15 (the length direction being
perpendicular to Figure 3) is formed in the outside
surface of the molded article, which trench has a shape
substantially complementary to the shape of the rail 12.
The foam extends all the way around the overmolded
element 1 except over its inside faces below the end
edges and except over the bottom of the open internal
space. In particular, the foam extends until it covers
the top surfaces of the two side walls 3 and 4 to the
innermost points 5 and 6 of the top edges of the two
walls. The foam defines two vertical faces 50 and 51 of
the trench, which vertical faces extend from the top
CA 02787355 2012-07-16
22
opening of the trench that opens out onto the outside of
the molded article to the respective top edges of the
walls 3 and 4 forming the branches of the U-shape of the
overmolded article. The hook-free end segments of the
inside surface of the overmolded article are
substantially parallel and in continuity with the
vertical faces 50 and 51. The transition from the
vertical faces 50 and 51 to the respective inside
segments takes place smoothly, without any unevenness, in
particular at the join.
Figures 3A, 3B, and 3C show portions of respective
resulting molded articles. Naturally, depending on the
molded article, it is possible to provide a plurality of
trenches of this type, each of which is provided with at
least one element having hooks of the invention. In
particular, it is possible to provide a pedestal of very
long length that is clamped by a plurality of spaced-
apart overmolded elements in order to obtain a trench
having a plurality of spaced-apart overmolded elements at
its bottom.
Once the molding of the foam article including one
or more overmolded elements having hooks is finished,
and, in particular, when the molded article is a motor
vehicle cushion, it then needs to be covered with a cover
or with a covering. This cover is connected to elements
having loops that come to co-operate with the hooks to
fasten the cover to the molded article while covering it,
in particular by fitting snugly over the shape of its
outside surface.
An element having loops of this type is shown in
Figure 6. It is provided with a pocket 20 constituted by
a sheet of textile material folded over onto itself,
loops stemming from the outside surface of the pocket.
These loops 21 may, in particular, have been woven or
knitted into the outside surface of the pocket 20. Two
pieces in the shape of sheets 22 and 23 forming the cover
are superposed at their edges and the pocket is sewn to
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23
the side (see Figures 13 and 14) of the two edges so as
thus to join the two sheets 22 and 23 to form the cover.
Thus, the pocket 20 that lies at the join between the two
sheets 22 and 23 is inserted into the bottom of the
trench 15 so that the loops come into contact with the
hooks so as thus to fasten the cover around the molded
article, in particular along the outlines and the walls
of the trench 15.
Figures 7 and 8 show side views (with the molded
article having been omitted) of the fastening between the
hooks and the loops. Two overmolded elements 1 having
hooks have been placed at the bottom of the trench by way
of illustration. Naturally, the trench may extend
lengthwise over a longer distance in order to provide
more than two elements having hooks therein.
In addition, a wire 24 that is, in this example,
constituted by a circularly cylindrical bar of rigid
plastics material has been inserted into the pocket 20 of
the element having loops in order to stiffen the overall
assembly. The rigid wire of plastics material is, for
example, made of polypropylene (PP) or of polyethylene
(PE), and has a diameter of at least 2 mm. However, it
is also possible to provide a hollow wire, i.e. a tube-
shaped wire. When the rigid wire 24 is not present
inside the pocket 20, then, in the intermediate zone
between the two elements 1 having hooks, a riding-up
effect occurs in that the pocket 20 tends to ride up,
i.e. to arch, so as to deform in the manner of a tent, as
shown in Figure 7.
Conversely, when the rigid wire 24 is placed inside
the element 20, the riding-up effect disappears, as shown
in Figure 8. Thus, the two elements 1 shown in Figure 7
are spaced apart at a distance such that, when there is
no wire 24, there is a riding-up effect and when there is
a wire 24 placed inside the pocket 20, there is no
riding-up effect. In particular, this distance may
correspond to a distance greater than in the range 20 mm
CA 02787355 2012-07-16
24
to 25 mm, given that it can easily reach 80 mm, or indeed
in the range 150 mm to 200 mm.
As indicated, in Figure 4A, the thickness D of the
rail 12 preferably lies in the range 8 mm to 16 mm, and
even more preferably in the range 9 mm to 12 mm. These
ranges of thickness dimensions are, however, also valid
for the other embodiments shown in the drawings.
In the embodiment corresponding to Figures 3B, 4B,
and 5B, the pedestal tapers going downwards (i.e. in the
direction indicated by the arrow F). This results in a
trench shown in Figure 3B that has its width tapering
towards the top opening. As in the embodiment of
Figure 3A however, the innermost points 5 and 6 of the
top edges of the two walls do not stand proud from the
two faces 50 and 51 of the groove 50. The same applies
in the embodiment shown in Figure 3C.
Figure 11 shows the assembly of Figure 8 in a cross-
section through the trench 15. The width of the trench
is measured horizontally to the figure. The sum of the
diameter of the wire and of twice the thickness of the
sheet folded over onto itself to form the pocket is
substantially equal to the width of the trench. In
particular, the pocket and each wall of the trench come
flush with each other.
Figure 12 shows another embodiment in which the wire
is of oval or elliptical section having its major axis
extending in the direction vertical to the figure, i.e.
from the bottom of the trench towards the outside. The
total width of the element having loops (dimension along
the minor axis and twice the thickness of the pocket) is
substantially equal to the width dimension of the trench.
In the present Application, the mutual fastening
between the molded article and the cover is described as
being by hooks stemming from the molded article co-
operating with loops on the cover. It should be noted
that it is also possible to provide hooks instead of the
loops, which hooks then co-operate with the hooks on the
CA 02787355 2012-07-16
overmolded elements in the manner of a hook-in-hook self-
fastener, and that is why, in the claims, the term "loop"
should be understood in a broader acceptation that also
encompasses the fact that the loops may be hooks.
5 Figure 15 shows an embodiment of a molded article
having a trench extending non-straightly, and, in
particular, including curved segments. Since the
overmolded elements do not need to be placed
continuously, and in particular end-to-end in the trench,
10 the assembly is simplified and in particular it is not
necessary to provide overmolded elements of curved shape
complementary to the shape of the curved segment of the
trench, the same elements of short length and spaced a
long way apart used in the straight segments also being
15 suitable in curved segments of low curvature.
In the present Application, the term "hook" means
any element having the capacity to hook, in particular
into a loop. In particular, a hook is an element
comprising a shank and a head projecting laterally from
20 said shank. Thus, elements in the shapes of a mushroom,
of a barb, of a double head, or of some other analogous
type are hooks in the meaning of the invention.
In the first and third aspects of the invention, the
mutual fastening between the molded article and the cover
25 is described as being by hooks stemming from the molded
article co-operating with loops on the cover. It should
be noted that it is also possible to provide hooks
instead of the loops, which hooks then co-operate with
the hooks on the overmolded elements in the manner of a
hook-in-hook self-fastener, and that is why, in these
first and third aspects of the invention, the term "loop"
should be understood in a broader acceptation that also
encompasses the fact that the loops may be hooks.
Conversely, in the second aspect, the term "loop" implies
the existence of an opening through which a hooking
element can pass and be hooked.
CA 02787355 2012-07-16
26
Similarly, within the ambit of the first aspect, it
is possible to make provision for it to be used with a
single overmolded element or with a plurality of such
elements over any given pedestal, in which case it is
possible to place them some distance apart from one
another (this then lies within the ambit of the first
aspect of the invention) or, very close together, or
indeed end-to-end if so desired.
